Combination torque distributor and differential



Sept. 7, 1937. W E 2,092,128

COMBINATION TORQUE DISTRIBUTOR AND DIFFERENTIAL Filed Feb. 16, 1935 2 Sheets-Sheet l v INVENTOR.

a FRANK P. LAWLER F I G. 2 BY j I 2 ATTORNEYS.

F. P. LAWLER Sept. 7, 1937.

COMBINATION TORQUE DISTRIBUTOR AND DIFFERENTIAL 2 Sheets-Sheet 2 Filed Feb. 16, 1935 Patented Sept. 7, 1937 UNITED STATES COMBINATION TORQUE DISTRIBUTOR AND DIFFERENTIAL Frank I. Lawler, San Francisco, Calif., assignor to The Torque-Distributor 00., a corporation of Nevada Application February 16, 1935, Serial No. 6,847

4 Claims.

This invention relates to a combination torque distributor and differential of the type disclosed in my former Patent Number 1,920,994 entitled Torque distributor, issued August '8, 1933, and particularly'to the application of the torque distributor to a conventional type of difierential.

The conventional differential used in conjunction with the driving axles of automotive vehicles is a highly efficient device as long as the two driving wheels have equal traction, but it immediately becomes inefficient when a difierence in traction is encountered. V

The differential would be a perfect mechanism if it were not for the fact that it can not under any circumstances deliver more torque to one drivingwheel than it does to :the other. This faulty characteristic would not be objectionable if thetractability oi the two driving wheels always remained equal, but it is well known that in driving, conditions are often met where there is a great difierence in the .tractiveness of the two wheels as when one encounters a slippery surface or .mudho'le and the other' remains on a highly tractive surface. This one defect in the conventional differential results-first in a general loss in the tractability of the driving wheels, that is, the moment a difiference in tractive surface is encountered by the two wheels the wheel with the greatest traction can only deliver as much torque :as the wheel with the ,least traction andany added traction which it has available is lost; and, secondly, where a difference in trac- -tive surface .is encountered, particularly on slip- ,pery or wet ground, the wheel encountering the least resistance will tend to spin and often stall or .mire the vehicle. I

i Theobject of the present invention is to retain the good :or efficient features of the conventional diiferential and .in addition thereto, to provide means whereby spinning of one wheel withrelation to the other is prevented and whereby torque is automatically transmitted to the wheels substantially in proportion to their tractive-ability. I

The combined torque distributor and differential is shown by way of illustration in-the accompanying drawings, in which Fig. -1 is a central, horizontal, longitudinal section-through thecombined torque distributor-and differential.

Fig. 2 is across section "taken'on 1ine IIII of Fig. 1, said view also diagrammatically.indicating the wheel drivenby the adjacent axle.

.Fig. .3 isra cross sectiontaken on line III-III of Fig. 1. p

Fig. i is .a longitudinal section showing a slightly modified form of the combined torque distributor and differential.

- Fig. .5 is a =cr0ss section tak n n line V'V of Fig. 4.

Fig. 6 is a perspective view of the spider. Fig. '7 is a perspective view of one of the side compensating gears shown in Fig. 1.

Fig. 8 is a perspective view of one of the axle inner ends.

Fig. 9 is a perspective view of one of the torque distributing pins.

Referring to the drawings in detail, and particularly Fig. 1, A indicates a differential case divided into two sections 2 and 3. The sections are secured together by bolts 4 to permit the pins 5 of the spider 6 to be clamped between them.

The case is supported in bearings l and 8 disposed at opposite ends of the axle housing and is driven by gear 9 and pinion Ill secured on the propeller shaft I l.

The pins 5 of the spider carry the usual pinions 12 and these mesh with compensating side gears l4 and I5 journaled at opposite ends of the case. The axles indicated at l6 and I! extend into opposite ends of the case and their inner ends are enlarged, as indicated at Mia and Ila, and are journaled in the case for purposes hereinafter to be described.

The axles in place of :being splined to the compensating gears are in this instance connected to them by pins 18 and I9, which will hereinafter be referred to as torque distributing pins. In the present instance only one pin is employed in conjunction with each side compensating gear and adjacent axle, but two or more may be employed. The torque distributing pins are each provided with a spur gear pinion 2!] on the inner end and these pinions mesh with an internal gear 2! formed within the spider ring 6. The torque distributing pins are carried by and are 'journaled. in the compensating side gears M and i5 and they are also rotatable with relation to the enlarged inner ends of the axles into which they extend.

By referring to Figs. 7 and 8, it .will be-clearly seen that an opening is formed in the compensating gear for the reception of the torque distributing pin and that a similar opening is formed in the enlarged inner end of the axle for the reception of the outer end of the torque distributing pin. i

The difierential mechanism illustrated is of conventional construction throughout withthe exception of the formation of the internal gear 2| within the spider ring which actuates the spur gear pinions 20, or in other words the torque distributing pins which connect the compensating gears and the axles driven thereby. By this slight change and addition to the conventional diiferential it becomes possible to retain all of the good features of the conventional differential, and in addition thereto, it becomes possible to prevent spinning of either driving wheel with relation to the other and, further, to

transmit the power delivered by the differential to the respective axles and wheels in substantial proportion to the tractability of the same.

Before describing the operation of the mech anism as a whole, particular attention will be directed to Figs. 1 and 2. To begin with, if a vehicle is traveling in a direct or straight line and if both wheels travel over a surface affording equal traction the mechanism will function as a conventional differential. That is, the power delivered to the case through the gears 9 and l0 will be transmitted through the spider pinions to the compensating side gears M and i5 and from them through the torque distributing pins l8 and I9 to the respective axles in the form of. torque; and. the torque will be equally divided between the two axles and wheels. On the other hand if the surface over which the wheels travel changes, for instance if one wheel encounters a wet or slippery surface the driving force exerted in the conventional differential tends to spin the wheel affording the least traction. This, as previously pointed out, is the one defect of the conventional differential. This defect may be referred to as an advantage of the present structure as it is the tendency of the driving force to spin the wheel having the least traction which is harnessed and utilized to prevent spinning. The manner in which this is accomplished is best illustrated in Fig. 2, in which A indicates the case or driving member, ma the enlarged inner end of the axle, M the torque distributing pin, and 25 the driven wheel or tire.

By again referring to Fig. 2 it will be noted that the pin I8 assumes an eccentric position with relation to the enlarged inner end Mia of the axle and that this eccentricity of the pin forms a pair of connected arcuate wedges, such as indicated at 25 and 21. e

7 During normal driving or under any driving condition the wheel 25 encounters a certain amount of resistance which varies with the degree of the tractability of the ground over which the wheel travels. This resistance is indicated by the arrow at, if the vehicle is traveling in the direction of arrow 1), the direction of the arrow a being reversed when the velncle is reversed.

. This resistance, as already stated, exists under any driving condition and it is also present even though the wheel leaves the ground and in that instance is due solely to the inertia of the parts. This resistance is important. as it is the force whereby one or another of the wedges 2 6 and 2'! are actuated. The wheel 25 is directly connected to the axle of which l6a is a part, hence the resistance is also present in the axle and the direction of resistance is indicated by the arrow 0 when the vehicle is being driven in the direction of arrow 1). It must now be pointed out that the axle and the wheel secured thereto is driven solely by the pin l8 and as this is'the case the surfaces indicated at D and E will always be loaded and maintained in intimate contact with relation to each other, this'loaded condition being due to the resistance indicated by the arrow 0. It has previously been stated that thedriving force which tends to spin the wheel affording the least resistance when a conventional differential is employed, is the force which, in the present invention, is utilized to prevent spinning. The manner in which this force is utilized will now be described. Q

If surfaces of unequal traction are encoun tered by the respective wheels the driving force transmitted to the case Will QbV QIlS Y tend to spin the wheel encountering the least resistance. Before spinning canactually take place, and assuming it is the left hand wheel and axle which affords the least resistance, the compensating gear 94 will have to speed up with relation to the case A, and if it does speed up it will tend to rotate the torque distributing pin l8 in the direction of arrow f, see Fig. 2. This can be clearly seen by referring to Fig. 3; that is, if the compensating gear runs ahead of the case A it will also run ahead of the spider ring 5, which is secured to the case and as the torque distributing pin and the spur gear pinion 20 are carried by the gear M, rotation will be transmitted to the pin in a direction of arrow 1, Fig. 2. This tendency of the compensating gear to drive the axle at a greater speed than the case causes the case to rotate relative to" the axlein the direction of arrow g, see Fig.2, thereby causing an instantaneous clutching action between the wedge 26 and the surfaces D and E, as the wedge is driven between these surfaces by the tendency of the resistance C to always force or .drivethe wedge in the direction of arrow .0. This automatic clutching action or coupling action locks the three members with relation to each other, or tends to do so, and when they look the entire differential mechanism is secured against. differential action, and when this occurs spinning of the axle and wheel is prevented and the torque,

and power which would normally be dissipatedin spinning the wheel encountering the least resistance will in this instance be transmitted'to the other axle. Hence, it can be seen that by this means and by the addition of the two simple torque distributing pins to the conventional differential, it is possible to (at desired times) transmit more torque to one wheel than to the other, thereby correcting the fundamental fault of the differential gear, namely, its being limited to equal torque distribution to both wheels at all times.

The degree of lock or clutching action obtained in a structure of this character depends largely upon the angularity of the surfaces presented by the arcuate wedges 26 and 21, and as these angular surfaces can be varied by changing the size and the eccentricity of the pin l8, any degree of lock or clutching action can be obtained from zero to one hundred per cent. Because of this extremely desirable flexibility of design, it is possible to effectively combine, in a single construction, all of the good features of the conventional differential gear with all of the good. features of a solid axle, and to make the percentage of inter-axle lock or influence any desired Value. Also, by implying the two wedges 26 and 21, the wedge 26 will function when driving ahead and the wedge 2'! when reversing.

There are only two conditions under which the speed of rotation between the axles and the case tends to change. The first condition, to-wit, that which takes place when the driving force tends to spin the axle affording the least resistance, as described above; and the second condition is that created when the wheels are caused to travel at different speeds incident to rounding a corner.

Under the first condition only one force is pres- .ent in the axle, to-wit, the driving force delivered to the case through the propeller shaft and the gears 9 and I0. Under the second condition two forces are present, namely, the driving force and a secondary force generated by the wheels themselves, plus a small amount of power and force which is put into the steering wheel and which is forming a journal therefor.

construction all of the clutching action takes amplified by the lever arm through which the steering wheels act. In rounding a curve the outer wheel travels at a greater speed than the inner wheel, and it is under this condition that the secondary force is generated and tends to neutralize or relieve the resistance indicated by the arrow 0, see Fig. 2, and as it neutralizes or relieves this force on the wedge the clutching action between the members 16a, and I8 is prevented; hence permitting free compensating action and rotation of the Wheels relative to one another when the mechanism is acted upon by the secondary force.

Plainly speaking, the structure might be said to embody a difierential mechanism, together with a pair of axles driven thereby, and a pair of double acting clutches disposed one between each axle and the dilferential mechanism. These clutches are automatically actuated and when influenced by the secondary force are free, but whenever there is a tendency of the primary driving force to spin one axle with relation to the other the clutch on that side locks the differential mechanism and thereby prevents spinning of that axle and furthermore transmits a correspondingly greater portion of the available torque to the other axle.

The modified'construction, indicated in Figs. 4 and 5, shows a method whereby the case A can be relieved of all load incident to the clutching action. The compensating side gears l4 and 15 are shown as having cylindrical extensions [4a and I Bet surrounding the inner enlarged ends l 6b and Nb of the axles l6 and I1 and thus By means of this place between the cylindrical extensions Ma and [5a and their corresponding torque distributing drive pins l8 and I9. In this instance the compensating side gears simply float in the bearings in which they are journaled in the case A just as they do in the conventional differential, since their load is simply torque emanating from theoretically balanced couples. This construction has the advantage that it allows all of the parts which function in the clutching action to be made of extremely hard steel while the case can be made of much softer and cheaper material. In operation no appreciable rotational movement takes place between the enlarged axle ends 16b and [lb and the cylindrical extensions Ma and l5a, such movement as does take place being limited by clearance between the parts. For a given degree of eccentricity and corresponding proportion of the parts the clutching action in the construction shown in Figs. 4 and 5 will be considerably modified over that shown in Fig. l, but this is not objectionable since varying classes of work require a varying degree of inter-axle infiuence or lock, and as has been pointed out before, it is a distinct advantage to be able to vary the degree of control which one axle has over the other over a wide range so that the unit can be designed for the most efficient point to suit diversified conditions of operation.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. In a differential mechanism a power driven case, a rotary set of differential gears journaled in the case, said gears including a pair of side compensating gears, a pair of axles, one for each side compensating gear, a pin carried by each side compensating gear and projecting into the adjacent axles and forming a driving connection between said gears and axles, said pins being eccentric with relation to the axis of rotation of the said gears and axles, and means actuated by said pins for securing the differential gears against differential movement when the power transmitted to the differential gears tends to spin one of the axles with relation to the other.

2. In a differential mechanism a power driven case, a rotary set of differential gears journaled in the case, said gears including a pair of side compensating gears, a pair of axles, one for each side compensating gear, a pin carried by each side compensating gear and projecting into the adjacent axles and forming a driving connection between said gears and axles, said pins being eccentric with relation to the axis of rotation of the said gears and axles, said pins being rotatable with relation to said gears and axles, means for rotating the pins when the power transmitted to the differential gears tends to spin one axle with relation to the other, and means actuated by rotation of the pins for securing the differential gears against difierential movement.

3. In a differential mechanism a power driven case, a spider secured in the case, a pair of side compensating gears supported in the case, pinions journaled on the spider and intermeshing with the side compensating gears, a pair of axles one for each side compensating gear, a pin carried by each side compensating gear and projecting into the adjacent axle and forming a driving connection between the side compensating gear and the axle, said pins being eccentric with relation to the axis of rotation of the side compensating gears and the axles, said pins being rotatable with said gears and axles, a pinion gear secured on each pin, an internal gear secured to the spider and intermeshing with the pinion gears, said internal gear adapted to impart a rotary movement to the pins when the power transmitted to the differential gears tends to spin one axle with relation to the other, and means actuated by rotation of said pins for securing the differential gears against differential movement.

4. In a differential mechanism a power driven case, a spider secured in the case, a pair of side compensating gears supported in the case, pinions journaled on the spider and intermeshing with the side compensating gears, a pair of axles one for each side compensating gear, a pin carried by each side compensating gear and projecting into the adjacent axle and forming a driving connection between the side compensating gear and the axle, said pins being eccentric with relation to the axis of rotation of the side compensating gears and the axles, said pin being rotatable with said gears and axles, a pinion gear secured on each pin, an internal gear secured to the spider and intermeshing with the pinion gears, said internal gear adapted to impart a rotary movement to the pins when the power transmitted to the differential gears tends to spin one axle with re lation to the other, and a pair of clutching members actuated by rotation of said pins, said clutching members securing the differential gears against differential movement.

FRANK P. LAWLER. 

